"This is a localized tumor," noted Bogea. She added that the tumor has not metastasized, a characteristic of most cancerous cells.

The former president left office due to term limits, and was succeeded by his preferred candidate, Dilma Rousseff, the country's first female president. The cancer diagnosis, Global Post notes, could put a wrinkle in what many believed was Lula's plan: a run to reassume the presidency in 2014, after his term-limited exile.

News reports are focusing on the Germanwings pilot's possible depression, following a familiar script in the wake of mass killings. But the evidence shows violence is extremely rare among the mentally ill.